I just installed mine yesterday, with the stock trigger spring, the Apex sear/spring, and the USB kit the trigger pull was 4.3lbs, then I installed the Apex trigger spring and the pull went up to 5.6lbs and the overtravel was reduced substantially. I fired about 50 rounds fairly fast with the trigger at 4.3lbs and had a couple go before I wanted them to, so for me 4.3lbs was just a little lighter than I want for a carry gun. I think if there was a little less take up like my 1911's the lighter trigger would be OK but I really can't 'feel' the break coming like I can with the 1911, so for me the 5.5lb trigger is preferrable. The reduced overtravel also eliminated the front sight shake I would get, no matter how carefully I applied pressure.